1. Field of the Invention
The present invention relates to a ultrasonic diagnostic apparatus, and more particularly to a ultrasonic diagnostic apparatus in which is performed electronic sector scanning of the ultrasonic transducers and mechanical compound scanning of the ultrasonic transducers along a selected body surface over the organs to be diagnosed and the combination of the above mentioned two scanning methods can easily select a picture image by selected display modes.
2. Description of The Prior Art
In FIG. 1 is shown a block diagram of a conventional electronic sector scanning ultrasonic diagnostic apparatus. In this prior art device an electronic sector scanning probe 10 in which a plurality of ultrasonic transducers are arranged at equal distances from each other transmits and receives ultrasonic beams to and from a body to be examined by means of sector scanning.
In order to control transmitting and receiving actions a transmitting-receiving control circuit is prepared. The transmitting-receiving control circuit 12 includes a repeating pulse generator 14 producing repeating pulses which are supplied to a transmitter-receiver 18 by way of an ultrasonic transducer control signal generator 16. The transmitter-receiver 18 supplies driving signals having a predetermined delay time to the selected transducer of the probe 10 to control the transmitting and receiving actions of the probe 10. The above mentioned driven ultrasonic transducer group is controlled to work one after another at every repeating cycle to perform well-known electronic scanning action. After the signals received by the transmitter-receiver 18 are detected by a detector 20, the signals are converted into echo signals having luminance in accordance with the strength of received echo by a luminance modulation voltage generator 22. The output from the transmitting-receiving control circuit one provided to a digital scanning convertor 24.
The digital scanning convertor 24 memorizes and stores the echo signals, and further, includes frame memory and signal convertor to perform requested signal conversion. The digital scanning convertor 24 also receives input synchronized signals from the repeating pulse generator 14. The output from the convertor 24 is supplied to a display section 26 composed of a standard television picture screen, etc. to display real-time dynamic picture images by sector scanning so that examiners can be provided with required diagnostic information.
In the prior art device shown in FIG. 1, as described heretofore, sector scanning images of the portion to be examined can be displayed in real-time, but a wider area of the body to be examined cannot be observed at the same time.
In the prior art device, it is possible to continuously display the sector scanning picture images of wider area by the scanning of the probe in manual operation or the like along the elected body surface over the organs to be diagnosed. Since, in this case the sector picture image is displayed at a fixed position on the picture display screen, and the actual probe position cannot be informed in the display area, and further, the examiner must always consider the relation between the displayed picture image and the position of the probe 10 in the diagnostic area, it is difficult to diagnose with accuracy and mistaken diagnosis can result.
As described hereinabove, in the prior art device, the electronic sector scanning and the compound scanning cannot be combined, and the real-time picture image updating cannot be halted at a selected time phase. In other words, still picture images of moving organs at predetermined time phases, sytole or diastole for example, cannot be recorded for diagnosis from a plurality of different position over the body surface and displayed as one picture image by means of overlapping such images.